Approximately 17.6 million Americans meet criteria for alcohol abuse or dependence, and 12.5 percent of individuals who meet criteria for alcohol abuse or dependence (2.2 million Americans) will receive treatment for an alcohol problem. Of those who receive treatment, the majority of individuals will have at least one drink in the first 12-months following treatment. The proposed study aims to delineate patterns in post-treatment drinking during the first year following alcohol treatment. Data from Project MATCH, a multi-site investigation of alcohol treatment sponsored by the NIAAA, will be used to test the hypothesis that there is significant variability in the drinking behavior between individuals and within individuals across time. Secondary data analyses of the Project MATCH data will be conducted for three distinct purposes. The first goal of the proposed study will be to replicate previous research using latent growth mixture modeling to investigate common patterns and individual differences in trajectories of drinking after the initial post- treatment drink. The second goal is to describe the differences in drinking trajectories using a biopsychosocial model of relapse risk factors. The third goal is to quantify the complexity of the relapse process by extending the latent growth mixture models to analyze the behavior of individuals who transition in-and-out of abstinence. The goal of these analyses is to understand why and when individuals experience major shifts in drinking over time. The major aim of the proposed research is to provide an empirically-driven model of relapse that incorporates the individual variability and abrupt, discontinuous nature of the relapse process, as illustrated in theoretical and qualitative reports. The ultimate goal of this inquiry is to provide clinicians and their clients with a heightened awareness of risk factors that may predispose an individual to heavy drinking and those factors that increase the probability of transitioning from light-to-heavy drinking following treatment. [unreadable] [unreadable] [unreadable] [unreadable]